Chronic pain plagues approximately 50 percent of community dwelling older adults, and may cause significant disruption of physical, psychosocial, and cognitive function. Despite the prevalence of this potentially devastating problem, well-controlled studies of chronic pain in older adults that use a comprehensive multidimensional model are lacking. Chronic low back pain (CLBP) is among the most common chronic pain conditions of older adults, affecting approximately 6 million individuals in the United States who are greater than or equal to age 65. CLBP offers a robust model with which to study the comprehensive functional effects of chronic pain in the older adult because of the reliable and valid measures of observed physical capacity, self-reported disability and pathology that have been developed specifically for patients with low back pain. The purpose of this investigation is to broaden our understanding of disability in the older adult with chronic pain. Specifically, we will explore (1) the magnitude of the effect of CLBP on physical, psychosocial, and cognitive functioning in 200 community dwelling older adults greater than or equal to age 65 as compared with 200 pain-free control subjects, (2) the impact of CLBP associated psychosocial and neuropsychological dysfunction on physical function, and (3) whether older adults with chronic pain can be classified using a multiaxial taxonomy that has been demonstrated in younger chronic pain patients. The laboratory-based physical capacities testing protocol is designed to assess body mechanics, endurance and coordination using ergonomically relevant tasks (e.g., lifting, reaching). Other comprehensive multidimensional assessment measures will include those that have particular relevance to older adults, such as pain intensity, clinical measures of physical performance, disability, sleep, mood, self- efficacy, detailed measures of neuropsychological function, and self perceptions of health and well-being. This study represents the first well-controlled, comprehensive examination of the effects of chronic pain on individuals who may be most threatened by the risk of functional decline, that is, community dwelling older adults. Once the effects of chronic pain have been comprehensively described, only then can effective treatment programs be developed to help ameliorate the suffering of these older Americans.